Near Ultraviolet Absorption Spectra of Melamine and Some Related Compounds

1950 ◽  
Vol 18 (4) ◽  
pp. 434-437 ◽  
Author(s):  
George W. Costa ◽  
Robert C. Hirt ◽  
D. J. Salley
Keyword(s):  
Absorption Spectra ◽  
Ultraviolet Absorption ◽  
Near Ultraviolet ◽  
Related Compounds

Colouring Matters of Australian Plants. II. Naphthoquinones from Diospyros hebecarpa A. Cunn

1952 ◽  
Vol 5 (4) ◽  
pp. 760 ◽  
Author(s):  
RG Cooke ◽  
H Dowd
Keyword(s):  
Absorption Spectra ◽  
Ultraviolet Absorption ◽  
Ether Extraction ◽  
New Compounds ◽  
Related Compounds

Ether extraction of Diospyros hebecarpa A. Cunn. yields plumbagin, and two new compounds which are shown to be 5-hydroxy-7-methyl-1,4-naphthoquinone and 1,4-diketo-5-hydroxy-7-methyl-1,2,3,4-tetrahydronaphthalene. The ultraviolet absorption spectra of these and related compounds are recorded, and the synthesis of 1,4,5-tri-methoxy-7-methylnaphthalene is described.

scholarly journals The Near-ultraviolet Absorption Spectrum of Diimide Vapor

1974 ◽  
Vol 52 (6) ◽  
pp. 1006-1012 ◽  
Author(s):  
R. A. Back ◽  
C. Willis ◽  
D. A. Ramsay
Keyword(s):  
Absorption Spectrum ◽  
Bond Length ◽  
Gas Phase ◽  
Absorption Spectra ◽  
Ground State ◽  
Ultraviolet Absorption ◽  
Ultraviolet Absorption Spectrum ◽  
Near Ultraviolet ◽  
Bending Mode ◽  
Franck Condon

Absorption spectra of N2H2 and N2D2 in the gas phase have been obtained in the region 3000–4300 Å, consisting of about 30 diffuse bands for each compound. Long progressions in the spectra are attributed to excitation of the H—N=N bending mode, v2′, in the upper state, with much shorter progressions arising from the N=N stretching mode, v3′; values of v2′ = 1215 and 910 cm−1 and v3′ = 1550 and 1440 cm−1 were estimated for N2H2 and N2D2 respectively.The spectra are attributed to the 1Bg ← 1Ag(π* ← n+) transition of trans diimide, probably made allowed by vibronic interaction. From Franck–Condon calculations the H—N=N angle in the upper state was estimated to be 132 ± 2°, an increase of 25° from the ground-state value; the increase in the N=N bond length was estimated to be about 0.05 Å.

TRYPTAMINES, CARBOLINES, AND RELATED COMPOUNDS: PART IX. THE CYCLIZATION OF SOME NITRO- AND AZIDO-PHENYLPYRIDINES. PYRIDO[1,2-b]INDAZOLE

1961 ◽  
Vol 39 (12) ◽  
pp. 2516-2528 ◽  
Author(s):  
R. A. Abramovitch ◽  
K. A. H. Adams
Keyword(s):  
Absorption Spectra ◽  
Catalytic Reduction ◽  
Nitro Compounds ◽  
Ultraviolet Absorption ◽  
The Other ◽  
Azo Compounds ◽  
Minute Amount ◽  
Ferrous Oxalate ◽  
Related Compounds ◽  
General Method

Heating 2-o-nitrophenylpyridine with ferrous oxalate gives rise to pyrido[1,2-b]indazole (III). The evidence for the structure of this compound is discussed. Similarly, heating 2-o-nitrophenylpyridine methiodide and N-oxide with ferrous oxalate gives (III), in each case, demethylation and deoxygenation preceding the cyclization. In the latter case a minute amount of δ-carboline is also formed. Heating pyridine-N-oxides with ferrous oxalate is a potentially general method of effecting deoxygenations of these compounds. Contrary to the results of Smith and Boyer (11), it is found that heating 2-o-azidophenylpyridine also gives rise to (III). On the other hand, the action of heat on 2-o-azidophenyIpyridine-N-oxide gives a mixture of δ-carboline and δ-carboline-py-N-oxide in low yield. The mechanism of the cyclization of the azides and of the reaction taking place on heating nitro-compounds with ferrous oxalate is discussed briefly; the formation of a nitrene intermediate is favored.The catalytic reduction of 2-o-nitrophenylpyridine-N-oxide giving rise to the azoxy-, azo-, and hydrazo-derivatives is described and the ultraviolet absorption spectra of these compounds are discussed. It is concluded the steric inhibition of coplanarity exists in the azoxy- and azo-compounds leading to the lack of effective conjugation across the N=N bond.

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